# Effect of fluid balance situation within 7 days and early fluid intake after admission to the intensive care unit on in-hospital mortality and 1-year mortality in patients with cardiac arrest: a retrospective study from the MIMIC IV database

## TL;DR

This study found that higher fluid balance in the first week and early fluid intake in ICU patients who had cardiac arrest were linked to increased mortality rates.

## Contribution

The study identifies specific thresholds of fluid balance and intake associated with mortality in cardiac arrest patients using the MIMIC IV database.

## Key findings

- Fluid balance ≥38 ml.kg−1 within 7 days was linked to higher in-hospital and 1-year mortality.
- High fluid intake (≥147 ml.kg−1) in 24 hours was not associated with increased in-hospital mortality.
- Patients with fluid balance in the highest groups had significantly higher mortality rates.

## Abstract

The objective of this study was to assess the associations between the mean daily fluid balance within 7 days and fluid intake within 24 h after admission to intensive care unit (ICU) and mortality for hospitalization and 1-year in cardiac arrest (CA) patients.

Patients who experienced CA were enrolled from the Medical Information Mart for Intensive Care Database. CA patients were divided into <14, 14–37, 38–79 and >79 ml.kg−1 groups according to the interquartile range of the mean daily fluid balance. In addition, patients were divided into low (<147 ml.kg−1) fluid intake group and high (≥147 ml.kg−1) fluid intake group according to the median fluid intake within 24 h after admission to the ICU. Multivariate logistic regression models were constructed to determine the independent risk factors for in-hospital mortality and 1-year mortality.

The in-hospital mortality in the 38–79 ml.kg−1 and the >79 ml.kg−1 groups were higher than in the 14–37 ml.kg−1 and the <14 ml.kg−1 groups (P < 0.05). The 1-year mortality in the 38–79 ml.kg−1 and the >79 ml.kg−1 groups were higher than in the <14 ml.kg−1 group (P < 0.05). The 38–79 ml.kg−1 and >79 ml.kg−1 groups were associated with increased risk of in-hospital mortality [odds ratio (OR) 2.300, 95% confidence interval (CI) 1.381–3.831; P = 0.001; OR 2.691, 95% CI 1.515–4.779; P = 0.001] and 1-year mortality (OR 2.131, 95% CI 1.308–3.470; P = 0.002; OR 2.141, 95% CI 1.237–3.703; P = 0.006). The in-hospital mortality in the high-fluid intake group was higher than in the low-fluid intake group (P < 0.05). The 1-year mortality was not significantly different between the two groups (P = 0.055). A high fluid intake was not associated with an increased risk of in-hospital mortality (OR 0.841, 95% CI 0.587–1.204; P = 0.344).

Mean daily fluid balance ≥38 ml.kg−1 within 7 days after admission to the ICU was associated with increased in-hospital mortality and 1-year mortality in cardiac arrest patients. Fluid intake ≥147 ml.kg−1 within 24 h after admission to the ICU was not associated with increased in-hospital mortality in cardiac arrest patients.